Porous SiC ceramics have a large number of applications. They are often used under conditions involving high temperatures and/or corrosion activity. For example, they are used for exhaust gas cleaning at high temperatures as filters, for gas heating in pore burners, for solar installations, for heat treatment substrates. They are also used as catalyst carriers, combustion aids and insulators. It is thus necessary that porous SiC ceramics present a high stability at high temperatures, a high resistance to corrosion and a high mechanical strength. It is also necessary that a SiC ceramic have a high level of porosity with a desired pore size distribution.
Many engineering reports indicate that a major disadvantage of SiC is that it does oxidize to silicon dioxide (SiO2) relatively easily at high temperature, especially in humid environments. The micro structure of the ceramic changes during the oxidation process, which leads to reduction in bulk strength. This is illustrated for example in FIG. 1. In addition, high sintering temperature and non-homogeneity in the mixture of the starting material bring some limitations and significantly affect the cost as well as the efficiency of the final product.
Methods for the fabrication of SiC ceramics are known in the art. Such methods are disclosed for example in the documents listed herein in the References section at [1].
There is still a need for a method for the fabrication of porous SiC ceramics which allows for at least a certain degree of control over properties of the ceramic such as porosity, pore size distribution, mechanical strength at low sintering temperature.